It was almost one year ago when the European Space Agency’s Rosetta spacecraft intentionally crashed into Comet 67P/Churyumov-Gerasimenko. That effectively meant the end of the mission, as the ESA knew it, but the scientists behind Rosetta were in for a pleasant “surprise” earlier this week after discovering the last photo of Comet 67P before the spacecraft met its end.
The Rosetta spacecraft was launched by the ESA in 2004, and it took 10 years for the craft to reach its destination of Comet 67P. According to Space.com, Rosetta spent the next two years orbiting the comet, before intentionally crash-landing into its surface on September 30, 2016. Using the OSIRIS imaging instrument, Rosetta took several photos of the comet during the 14-hour descent period, and while almost all the images made it back to mission control, the last photo of Comet 67P was not fully transmitted back to Earth before Rosetta crashed into the touchdown site, which ESA researchers christened as “Sais.”
“The last complete image transmitted from Rosetta was the final one that we saw arriving back on Earth in one piece moments before the touchdown at Sais,” read a statement from OSIRIS camera principal investigator Holger Sierks.
“Later, we found a few telemetry packets on our server and thought, wow, that could be another image.”
— ESA Science (@esascience) September 28, 2017
Fox News explained that images of Comet 67P were divided into telemetry, or transmission data, before being relayed back to mission control on Earth. The last photo of Comet 67P was to be split into six packets, but due to the transmission getting interrupted after three entire packets were received, ESA scientists were left with slightly more than half of a complete image.
Rosetta’s automatic processing software did not recognize the three full packets out of six as an actual image, but the mission’s scientists were still able to work around the software’s limitations and use the remaining fragments to manually reconstruct what should have been the last photo of Comet 67P, and release the image on Thursday. Gizmodo noted that the photo was taken about 55 to 65 feet above the comet’s surface, with a view spanning about 10 square feet.
The manual reconstruction was made possible by Rosetta’s compression software, which encoded the image layer-by-layer, instead of pixel-by-pixel. According to Gizmodo, this also meant that the new photo would be lacking in detail, with the new compression ratio being 1:38, as compared to the normally expected figure of 1:20. As such, the final photo of Comet 67P came out “coherent, but blurry,” but since Rosetta’s camera wasn’t designed to focus, there’s a strong possibility that the image would have been blurry anyway, even if it was transmitted in full during the probe’s crash landing last year.
[Featured Image by ESA via Getty Images]